Hi and thank you for choosing HCM to post your question. I read carefully your question and understand your concern. A pulmonary solitary nodule can have a wide spectrum of differential diagnosis. Nodules between 2 to 5 mm have a 1% chance of being malignant. Other clinical carachteristics like your age,your smoking status,your medical history,the diameter of the nodule,the location of the nodule in the lung lobes ,help in narrowing the diagnosis between benign and malign causes and it is called pretest probability of cancer.If the nodule is 1cm or greater the biopsy is needed.But in your case ,the dimensions of the nodule were reduced in 2 mm.Your treating doctor need to evaluate your pretest probability of cancer and if you are considered low risk patient no follow up needed since your nodule size is 2 mm(less than 4 mm)If you are considered moderate or high risk patient ,for your nodule size i would recommend follow up CT scan at 12 month . I hope my opinion can be helpful. Wish you good health. Kind regards Dr.Dushi.